When and where was the first line of telegraph built?
The first line of telegraph was built in 1844, from Washington to Baltimore, by Professor Morse.
What is the principle of the telegraph?
At one end of the telegraph wire is an electrical battery, and at the other end is an electro-magnet. When a message is to be sent, the electricity is transmitted through the wire to the soft iron of the electro-magnet, which causes the iron to move, and this motion is conveyed to the machinery, which is needed to print the message in letters or signals, so as to be understood.
Does electricity move rapidly?
Yes; its velocity is such as to move around the earth in a quarter of a second.
What is the electrical battery called?
The electrical battery is called a key.
What is the electro-magnet called?
The electro-magnet is called a receiver.